Crown-tooth and pin therefor.



J. L. WILLIAMS.

CROWN TOOTH AND PIN THEREFOR.

APPLICATION FILED MAR. 6. 1915.

Lm fiwm PatentedAug. 10,1915.

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JAMES LEON WILLIAMS, OF PELHAM, NEW YORK, ASSIGNOR TO THE IDENTIS'ISSUPPLY COMPANY, A CORPORATION OF NEW YORK.

CROWN-TOOTH AND PIN THEREFOR.

intense.

Specification of Letters Patent.

Patented Aug. in, 19 15;.

Application filed March 6, 1915. Serial No. 12,485.

Therefor, of which the following is specification.

This invention relates to crowns for teethand more particularly to thepin for holding the tooth crown to the root of the tooth, and my objectis more especially to provide a construction in which the tooth crownshall be so supported and attached to the root that a greater strengthof union is secured than in the customary practice heretoforeen'iployed, and moreover to provide a con struction of pin which shallgive great stability against displacement of the tooth, whichdisplacement has heretofore been possible by the bending of the p n. D

My object is also to provide a pin in which the prong entering the rootand the prong secured in the crown tooth is offset sutliciently toenable the latter prong to extend down in the direction of the biting orincisor edge of the tooth in the case of front teeth, so that a greaterlength of pin may be employed and be surrounded with a more substantialportion of the porcelain.

My object is also to so shape the pm at the juncture of the tooth prongand the root prong that it shall provide a rearwardly eX- I tending heelfor receiving the upward thrust of the lingual portionof the tooth toprevent rotation of the tooth relatively to the root by the bending ofthe pin, and moreover to provide a pin structure which will effectuallyprevent the possible rotation of the tooth upon the pin about a verticalaxis, the construction being such that the pin cannot possibly turn inthe porcelain tooth structure.

lVith the above and other objects in View, the nature of which will bemore fully understood from the description hereinafter, the inventionconsists in the novel construction of the pin and its combination inassociation with the tooth as hereinafter more fully describedanddefined in the claims.

Referring to the drawings Figure l, is a vertical section througliatooth-root and a I tooth crown secured by a pin einlioilyiiig myinvention; Fig. 2 is a front elevation of the same; Fig. 3 is a planview of the tooth crown showing the recess for the pin; Fig. L is avertical section through the tooth crown on. i i of Fig. 3 and line ofFig. 1, with the pin removed; Fig. 5 is a perspective view of myimproved pin; Fig.

6 is an enlarged top view of the'sanie; and Fig. 7 is a perspectiveview\of the tooth crown.

Heretofore in practice it has\been customary to provide the tooth crownwith a pin having an extending prong fon insertion into the root of thetooth, in which the prongwas in alinement with the pin portion withinthe tooth structure. Furthermore; it is customary to bake the pin in thecrown so that the pin is a unitary structure with the tooth crown. Wherethe pin is in this manner rigidly connected with the porcelain crown itis often necessary to bend the prongs to insure proper positioning ofthe crown in the mouth. This weakens the construction both by possibleinjury to the pin and to the angularity given thereto. Furthermore, inteeth as heretofore made eniploying straight pins, the location of thepin in the porcelain crown, to adapt it to the root, has caused the pinto be located objectionably far to the lingual. side of the tooth; andto secure the proper strength, it has been necessary to increase theporcelain at thisplace and thus deviate from the natuand pin 1 amenabled to overcome the above recited objections inherent in the formerpractice, and in accomplishing this I provide a pin structure in whichthe tooth prong and the root prong are definitely offset and the metalat the juncture of these prongs is widened, more particularly in thedirection of the offset to provide a heel at the rear of the prongs toengage the crown to ward the lingual side, and thereby more stronglybrace the crown against displacenient under hard usage, prevent anypossible capacity of the porcelain crown to rotate upon the pin, and toprovide full engagement between the pin and the crown without abnormalor excess iorcelain at the rear or lingual side. ll'lorcover. the metalin the pin is so thickened at the junction between the crown and theroot that there is no possibility of its bending under undue stress.

Furthermore; the construction of my improved pin and crown is such thatthe pin .may be employed separate from the crown,

and after .being cemented into the root the crown may be cemented to thepin and inposition upon the root and adjusted to the proper. positionwithout any necessity of bending the pin. 7

More'specifically referring to the drawings, 7 represents the root prongof the pin, which is substantially coaxial with a quasitriangularreinforcement or enlargement 8.

Projecting downwardly from the base of the. enlargement 8 is a crownprong 9, the axis. of which prong is substantially parallel to the axisof the root prong 7, and said prong 9 is located at the forward part ofthe base of the. substantially triangular enlargement 8, andthereforethe prongs 7 and .9;are in efi'ect'oflset with respect to each other.The I base of the enlargement 8 is also provided,

withga short downward projection 10 located at the rear part of the baseand opposite to where the crown prong 9 is located. Therefore, thesaidprojection 10 and prong 9 are opposite each other and .insubstantially parallel planes and the said projection '10 may be said toextend from the heel of the enlargement or reinforcement 8 andwhich heeland projection actas a brace for the tooth crown against backwardthrust;

The tooth crown 11, which is to be fitted with the pin, is provided witha suitable deep bore 12 adapted to receive the prong' 9, and withasubstantially trapezoidal or other suitable shallow recess 13 intowhich cemented in place and prevents any disfits the lower or base partof the reinforcement portion 8; This recess 13 of the crown, atthe'bottom and adjacent the side opposite the deep bore 12,'is. providedwith a'pocket 14 adapted to receivethe heel projection 10 of the pin.Itwill be seen from Fig. 1- that by offsetting the prong 9 from theprong 7 the bore 12 for the prong 9 in the crown 11, is formed near tothe front or labial part thereof, therefore leaving more-material forthe rear of the crown into" which theheel may be stepped. This is ofgreat importance, as the maximum stress applied tothe crown is alwaysfrom the rear, toward the front, and therefore the crown is greatlystrengthened when the bore 9 is made nearer 'to the front than to'therear, or contrary to what has heretofore been the general practice. Byengaging theheel projection 10 at the rear of the crown pin with thepocket 14 in the crown, I further brace the crown at the rear. Thereinforcement or body 8 .having its base fitting into the shallow recess13 while its prong 9 fits down into the bore 12 and its heel projectioninto the pocket 14, makes a strong 'connectionwhen placement bytorsional action.

Attention is called to the fact that inthe preferred form of myimprovedpin the heel portion at the junction of the crown and rootprongs is substantially dovetail in shape, as can be easily seen, moreparticularly in Figs. 2, 5 and 6. The heel reinforcement, which projectsinto the pocket. 11 of the cavity 15' of the crown locks the pinto thecrown when the cement is made to bind the crown with the root, as bestseen in Fig. 1. That'is to say, the cement 19 filling the cavity 15 andpocket 14 seals the crown pin to the crown and supplements thecementing'of the prong 9 in the bore 12 thereof. The partly engaged baseof the reinforcement 8, and also the heel projection'10, prevent theturning of the crown pin in the crown.. The prongs 7 and 9, either orboth, I

.may be indented or serrated asat 18, if deslredto more strongly holdinthe cement within the bore 12 of the crown and bore 16' g I of the toothroot 17.

The pin may be made of any suitable metal or metal alloy or of a'platedor coated metal if so desired, as I do not restrict myself .in thisregard. These pins may be cast,. forged, or stamped from sheetmetal; the,latter with a forging action to shape the parts is preferable,'bothbecause it pro-- duces a cheaper and stronger pin than by other methodsof manufacture.

From the foregoing description, taken in connection with theaccompanying drawings,

the advantage of the construction of my improved pin and crown,separately and combined, will be readily understood by'those skilled inthe art to which the. invention pertains; and it will be appreciatedthat the advantage of this improvement is that it effects a more widelydistributed and better balanced hold of'the pin on the porcelain crown,and gives afar stronger and substantially triangular reinforcementportion coaxialwith the rootprongiand having its lower end extendingboth to the front and to the rear of the root prong, said,reinforcern'ent portion having at the rear of its base a short heelprojection, and

more secure attachmentlto the natural root 7 at the forward end of itsbase a crown 2 prong having its axis substantially parallel to the axisofrthe root prong but out of axial alinement therewith.

heel projection arranged rearwardly from the junction of the said crownand root prongs, allpf the pin except the heel projection being ofsubstantially uniform thickness and the heel projection being of 5greater thickness at its lower part.

4. A tooth crown having its end which comes next to the root providedwith a deep bore and a rear pocket of greater width and greatly lessdepth than the bore and 20 connected therewith by a shallow recess.

In testimony of which invention, I hereunto set my hand.

v JAMES LEON WILLIAMS.

v Witnesses:

' J. R. SHEPPARD,

L ROY FRANTZ.

